of milwaukee



A. SIMON.

CIRCUIT BREAKER. APPLICATION FILED MAY 22. 1916.

1,315,42 v 'PatentedSept.9,1919.

' dul UNITED STATES PATENT OFFICE.

' ARTHUR SIMON, 0F MILWAUKEE, WISCONSIN, ASS IGNOB TO THE CUTLER-HAMMER MFG. 00., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

CIRCUIT-BREAKER.

I Specification ofLetters Patent. Patented Sept. 9, 1919.

Application filed Kay 22, 191 6. Serial No. 99,088.

To allwhom it may concern."

Be it known that I, ARTHUR SIMON, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee. and State of Wisconsin, have invented new and useful Improvements in Circuit-Breakers, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a art of this specification.

his invention relates to overload circuit breakers and more particularly to those having a time element.

It has heretofore been proposed to provide a variable time element for circuit breakers and to regulate the current value at which the same are adapted to .respond by introducing a regulable opposition to the movement of the solenoid plunger, whereby said factors may be varied jointly to some extent. This expedient, however, as applied to the ordinary type of solenoid produces a circuit breaker which is either unsensitive to momentary heavy overloa s or else is relatively unresponsive to small but persistent overloads, dependent.

upon whether the opposition to plunger movement is small or great, it being'impossible to lower the current value at which the device will begin to respond without cor' respondingly curtailing the time element within which actual opening of the controlled circuit may be avoided by receding of the overload peak.

The present invention has among its objects to overcome the foregoing dlfliculties and to provide a time element circuit breaker of increased sensitiveness to osi tive and negative variations in current rom a predetermined value.

" A furtherobject of the invention is'that ready adjustment of the timing means 0 such circuit breakers without disturbing the calibration thereof.

. Other objects will appear as the escript on proceeds.

In the accompanying drawing wherein is illustrated an embodiment'of the invention,

Figure 1 is a front View, partly in secof the prises a stationary contact 1 adapted for engagement by a movable 'contact 2 riveted upon a supporting arm 3 pivoted at 4 upon 'a fixed support 5 and biased to closed positlon by a coil spring 6 wound about saidpivot 4 and having one end engaging a lug 7 upon the contact member 2, the other end being bent to rest against the edge of the support 5. A downwardly projecting lug 9 is further attached to the supporting arm 3 to move therewith in proper relation to be engaged by the tripping means for disengaging said movable contact from said fixed contact.

The tripping solenoid includes a wind' 10 supported in a magnetic frame 11 an provided with a plunger 12, a;non-magnetic tube 13 surrounding said plunger and a magnetic plug 14; stationaril mounted in the lower end of said tube. The plunger is hollow and tapered at its lower end while the face of the plu is flat. i

The aforedescri d features of solenoid construction all cooperate to insure a plunger pull curve liavin the particular characteristics desired, v1'z., a prolongation of that portion of the curve representing a minimum increase in pull, and an adequate increase in ull near the end of the stroke followed su stantially at the end of the stroke by an abrupt termination of such increase.

The hollow character of the plunger and consequent distribution of the lines of force therein at a current value approximating that at which the solenoid is designed to begin its response insures against any. subsequent substantial increase in pull due to increase in flux component acting in the direction of motion of the plunger caused by changesin the flux distribution. Moreover by the cooperation of the tapered end of the plunger with the flat faced plug, the reluctance of the magnetic circuit decreases less rapidly during approach of said members than would occur if both surfaces were flat or of such contour as to fit one within the other. Both of these features thus tend to minimize the increase in pull of the plunger, or in other words, to prolong the portion of the stroke having a flat pull curve characteristic. Near the end of the stroke the reluctance decreases more rapidly owing to the rapid shortening of the air gap, between the plug and the advance portion of. the tapered plunger whereby a sufiiciently strong final pull is insured, while the final sealing between the plunger and plug occurs only along a line contact whereby sticking due to residual magnetism is minimized and a ready release insured, this characteristic being represented by an abrupt termination in the rise of the pull curve at the end of the stroke.

' The solenoid also has associated there with a dash pot 15. to retard the movement of its plunger and as will appear, the dash pot is so designed as to oppose the plunger substantially throughout that portion of its stroke characterized by the flat pull curve and to thereupon terminate its restrainmg effect to permit free movement of the plunger under the rapidly increasing pull exerted thereon at the end of its stroke.

The dash pot includes an oil cup 16 having a fixed cover 17 to which it is secured for support, said cover being fixed to the lower end of the solenoid frame and being fitted.

about the lower end of the non-magnetic tube 13. The cup has a lateral enlargement 18 provided with right angle assages 19 and 20 providing a bypass there or and said cup is of restricted internal diameter above the lower part of the bypass to receive a closely fitting-piston 21. The piston is connected by a stem 22 to the solenoid plun er and is provided with passages 23 afior ing communication between opposite ends of the cup. However, the piston is provided on its under side with a disk valve 24 to close said passages upon descent of said iston thereby necessitating displacement of t e oil through the bypass which, as will be understood, renders the dash pot effective for retardation of the solenoid plunger during its downward travel. When, however, the piston leaves the restricted bore of the cup and passes into the enlarged end of the cup the oil is ermitted free passage around the piston wlth a resulting free final'movement of the solenoid plunger and upon upward movement of the plunger the dash pot is rendered inactive by the free passage of oil through the openings in the piston.

The proportions of the dash pot are such that the piston will travel in the restricted bore during the stroke of the solenoid plunger characterized by the flat pull curve whereas it will enter theenlarged bore as the pull curve commences its abrupt ascent. Thus provision is made for a definite time element or in other words for a definite prolongation of the period in which the solenoid is rendered sensitive to slight negative current variations by reason of its accentuated flat pull curve characteristic. Also, the dash pot is provided with a screw plug 25 enabling regulation of the flow of oil through the bypass whereby said dash pot may be adjusted for variation of the time element.

The tripping lever 26 is pivoted at 27 upon a support 28 carried by the solenoid frame 11 and connected at one end by means of a pivoted link 29 to the upper end of the plunger 12 for actuation thereb Saidlever 26 carries an adjustable weig t 30 and an L-shaped trigger member 31, preferably of non-conductive material, spaced from the downwardly projecting lug 9 of the switch arm 3 and movable for engaging and tripping the same only after a predetermined movement of said lever, whereas adjustment of the Weight has no appreciable influence upon the time element of the switch 'as determined by the dash-pot setting.

The weight 30 of course determines the sensitiveness of response of the solenoid, or in other words, the sensitiveness of the solenoid to positive current variations, and being adjustable thus provides a convenient means for calibration. Moreover, the weight in any selected position rovides a load of substantially constant va ue irrespective of the angular position of the arm-supporting the same whereby the solenoid is unaffected by its movement.

The solenoid winding being connected in the circuit controlled by the switch 2 or an intermediate relay and the above described calibrating and timin means respectively ad usted for the current value and duration of overload beyond which protecoperation of the device tion is desired, the will be as follows: v

Excess of current will at once cause the solenoid to draw down its lunger and-thus force the piston of the o ash downwardly. The stroke of the plunger will thus be retarded to delay tripping of the Switch until the dash pot piston passes into the en larged bore. If the overload then continues the plunger will then be freed from m straint and the magnetic pull thereon will rise rapidly as above described with the rep unger 12 and the sult of accelerating its movement. The lever 26 will thus be operated to impart a hammer like blow to the switch 2 to open the same and thereby effect interruption of the overloaded circuit. This in-turn deenergizes the solenoid whereupon the weight 30 restores the arm and solenoid plunger to nitial position thereby permitting the switch to close under the influence of its spring.

If, however, the current recedes to a given value during the retarded stroke of the plunger the solenoid will release arm 26 before it efi'ects the opening of the sw tch and said arm will return to initial position under the influence of the weight. And here it is to be noted that owing to the accentuated flat pull curve characteristic of the solenoid it is sensitive to relatively slight negative current variations whereby the device may be calibrated with a minimum allowance for the differences in current values at which the solenoid will respond and release. In other words, the device may be safely calibrated to respond at a current valuervery closely approximating the maximum permissible current value.

In addition to the hereinbefore described s ecial construction and cooperation of the eludes other materia l a vantages. Among these are the exterior location and the construction of the bygass 19 whereby the valve plug 25 may be a justed without interference with the other elements or adjustments. It is also noted that fluid may be introduced into the dash pot 15 through said bypass 19 merely by removal of the plug 25. Furthermore, the tube 13, which is in fluid tight connection with the cover plate 17, functions to prevent escape of fluid from the dash pot.

.What I claim as new and desire to secure by Letters Patent is 1. In a circuit breaker, the combination with a switch, of a tripping solenoid therefor of the closed magneticcircuit type, said solenoid including means functioning to preserve during the latter part of the stroke of its plunger the abrupt pull curve characteristic typical of solenoids of such type while accentuating the flat pull curve characteristic thereof during an initial part of such stroke, and means opposing operation of the lunger of said solenoid, providing a time c ement incident to tripping of said switch.

2. In a circuit breaker, the combination with a switch, of a tripping solenoid there for of the closed magneti circuit type, said solenoid including means functioning to preserve during the latter part of the stroke of its plunger the abrupt pull curve characteristic typical of solenoids of such type while accentuating the flat pull curve char- 1 acteristic thereof during an initial part of 14:, the device inaccentuatin' the flat pull curve character-- istic thereo during an initial part of such stroke, and separatel adjustable means opposing movement 0 the plunger of said solenoid, providing respectively for a time element incident to tripping of said switch and for calibration of said solenoid to respond at different current values selectively.

4. In acircuit breaker, the combination with a switch, of a tripping solenoid there for of the closed magnetic circuit type, said solenoid including means functioning to preserve during the latter part of the stroke of its plunger the abrupt pull curve characteristic typical of solenoids of such type while insuring a substantially uniform pull of said solenoid throughout an increased initial por tion of such stroke and curtailment of its sealing pull, and means opposing operation of the plunger of said solenoid, providing a time element incident to tripping of said switch.

5. In a circuit breaker, the combination with a switch, of a tripping solenoid therefor of the closed magnetic circuit type, said solenoid including means functioning to pre serve' during the latter part of the stroke of its plunger the abrupt pull curve characteristic typical'of solenoids of such type while insuring a substantially uniform all of said solenoid. throughout an increase initial 'rtion ,of such stroke and curtailment of its sealing pull, separately adjustable means opposing operation of the plunger of said solenoid, providing respectively a variable time element incident to tripping of said switchand for calibration of the solenoid to respond at different current values selecwith a switch, of a tripping solenoid of the 4 closed magnetic circuit type said solenoid includin a fixed magnetic plug and a plun er aving' adjacent surfaces which are angu arly disposed to one another throughout the stroke of the latter, said plunger being of restricted cross sectional area for high saturation thereof, and means opposing operation of said plunger, but only during that portion of its stroke characterized by a substantially uniform pull, to provide a time element incident to tripping of said switch.-

8. In a circuit breaker, the combination with a switch, of a-tripping solenoid of the closed magnetic circuit type, said solenoid includin a fixed magnetic plug and a plunger iaving adjacent surfaces which are angularly disposed to oneanother throughout the stroke of the latter, said plun er being of restricted cross sectional area or 20 ready saturation thereof, adjustable means for subjecting operations of said plunger to different degrees of opposition substantially constant throughout each stroke, and inde pendent means opposing operation of said'25 plunger but only during that portion of its stroke which is characterized by a substan tially uniform pull.

In witness whereof I have'hereunto sub- 

